PBSC are collected from syngeneic donors in a similar manner. Patients undergo total-body irradiation twice daily on days -5 and -4. Patients receive cyclophosphamide IV on days -3 and -2 and anti-thymocyte globulin IV on days -5, -3, -1, 1, 3, and 5. Patients undergo autologous or syngeneic PBSC transplantation on day 0. Following PBSC transplantation, patients receive oral prednisone on days 7-30 and G-CSF IV daily beginning on day 0 and continuing until blood counts recover.